In current welded wire wall systems that use welded wire mesh with soil reinforcing comprising a horizontal floor portion, upright portions connect a facing panel together with a connection pin, tie wire, or hog rings. In certain of these systems, upwardly extending soil reinforcing elements have a series of kinks placed in them through which a connection pin is passed for connecting the facing panel to the soil reinforcing elements. The upwardly extending portions of the soil reinforcing elements in conjunction with the connection pin add steel to the earthen formation and increase the overall cost of the components.
Retaining wall structures that use horizontally positioned soil inclusions to reinforce the earth mass in combination with a facing element are referred to as Mechanically Stabilized Earth (MSE) structures. In MSE retaining walls, the size of the soil reinforcing wire diameter is dependent on the height of the wall and externally applied loads. As the wall height increases, the loads that are required to be resisted by the soil reinforcing elements are increased which in turn increases the requisite wire diameter of the soil reinforcing elements. As a rule of thumb, larger diameter soil reinforcing wire is placed in the bottom of the wall and smaller diameter soil reinforcing wire is used at the top of the wall. It is well known that the facing panel does not provide structural support of the MSE retaining wall, but rather the facing panel is used to prevent the soil disposed between soil reinforcing elements from raveling out of the face of the wall.
In systems that use soil reinforcing structures with upright portions and in systems that use soil reinforcing structures with an upwardly extending facing panel, upright portions are an integral part of the soil-reinforcing structure. Vertical wires of an upright portion and horizontal soil reinforcing wires are components of the same element. As the size of the soil reinforcing wire diameter increases, so does the size of the upright portions. Although the face panel does not structurally contribute to soil reinforcement, the wire diameter in the face panel is increased relative to the height of the wall system thus increasing the steel weight and subsequent cost of the wall system. A decrease in the overall cost of the wall system without changing the structural integrity of the MSE retaining wall may be realized by eliminating the upright portions of the soil reinforcing element and incorporating a separate facing element.
MSE retaining walls having separate face panels may advantageously be manufactured in various configurations allowing for different apparent, or accessible, openings at the face of the wall thereby allowing for the use of different sized, or granularity, backfill. Conventional MSE retaining wall systems that use upwardly extending L-type soil-reinforcing elements may feature a backing panel that is placed behind the upwardly extending soil reinforcing element or the facing panel. In these systems, the backing panel is used to decrease the accessible opening at the face of the wall to supplement the large accessible opening of the upwardly extending facing panel. The inclusion of a backing panel requires an additional fabrication step, additional material that must be shipped to the project, and an additional labor step in the erection of the earthen structure. Moreover, the inclusion of a backing panel increases the requisite steel weight of the MSE system. These manufacturing steps and material disadvantageously add to the MSE system weight, materials cost, and construction cost.
In MSE retaining wall design, the tributary area used to calculate the resistance of any soil reinforcing determined by assuming that the soil reinforcing element is located in the center of a three-dimensional volume of soil. The tributary of soil for this soil-reinforcing element is decreased by 50% when the soil reinforcing is placed on the foundation. In earthen retaining walls that use upwardly extending soil reinforcing elements, the bottom soil-reinforcing element has to be placed on the foundation, or separate elements have to be fabricated to move the soil-reinforcing element from the foundation.